Sandip Mukhopadhyay

Seasonal effects on the air–water carbon dioxide exchange in the Hooghly estuary, NE coast of Bay of Bengal, India

Monthly variation of CO2 fugacity (fCO2) in surface water and related atmospheric exchanges were measured in the Hooghly estuary which is one of the most important estuaries, since it is fed by one of the worlds largest rivers, the Ganges with a flow of 15,646 m3 s-1 (1.6% of the worlds combined river flow). Carbon dioxide fluxes averaged over the entire estuary are in the range of -2.78 to 84.4 mmol m-2 d-1. This estuary acts as a sink for CO2 during monsoon months and seasonal variation of its flux is controlled by dilution of seawater by river water. Since the solubility of CO2 and the disassociation of carbonic acid in estuarine water are controlled by temperature and salinity, the observed variations of CO2 fluxes are compared with those predicted from seasonal changes in temperature, salinity and the ratio of gross primary production to community respiration using empirical equations with an explained variability of 55%.

Impact of Sundarban mangrove biosphere on the carbon dioxide and methane mixing ratios at the NE Coast of Bay of Bengal, India

Abstract Diurnal and seasonal variations in carbon dioxide and methane fluxes between Sundarban biosphere and atmosphere were measured using micrometeorological method during 1998–2000. Study of the diurnal variation of micrometeorological conditions in the atmosphere was found to be necessary to determine the duration of neutral stability when flux estimation was reliable. Neutral stability of the atmosphere occurred in the limited micrometeorological conditions, when friction velocity ranged between 0.360 and 0.383 m s −1 . The value of drag coefficient (1.62–20.6)×103 obtained at variable wind speed could be deemed specific for this particular surface. 58.2% drop of carbon dioxide and 63.4% drop of methane in the atmosphere at 1 m height were observed during day time, between dawn and early evening. Diurnal variations in methane and carbon dioxide mixing ratios showed a positive correlation with Richardsons number (Ri). This environment acted as a net source for carbon dioxide and methane. The mixing ratios of methane were found to vary between 1.42 and 2.07 ppmv , and that of carbon dioxide, between 324.3 and 528.7 ppmv during the study period. The biosphere–atmosphere flux of carbon dioxide ranged between −3.29 and 34.4 mg m −2 s −1 , and that of methane, between −4.53 and 8.88 μg m −2 s −1 . The overall annual estimate of carbon dioxide and methane fluxes from this ecosystem to atmosphere were estimated to be 694 Tg yr −1 and 184 Gg yr −1 , respectively. Considerable variations in mixing ratios of carbon dioxide and methane at the NE coast of Bay of Bengal were observed due to the seasonal variations of their fluxes from the biosphere to the atmosphere. The composition was inferred by fitting model prediction to measurements.

Interactions of Cu (II) and Fe (III) with mangal humic substances studied by synchronous fluorescence spectroscopy and potentiometric titration

Humic (HA) and fulvic (FA) acids isolated from mangrove sediments of Sundarban, the largest delta on earth in the estuarine phase of the river Ganges, were studied and attempts were made to characterize their binding sites by quenching of Synchronous fluorescence (SyF) bands with Fe (III) and Cu (II). A modified Stern-Volmer relationship applicable for static quenching was applied for the determination of conditional stability constants and the data were compared with those determined by potentiometric titration. In the excited state HA and FA showed different acidity constant compared to the ground state. Values of the conditional stability constant (log Kc) for Fe (III) and Cu (II) indicated that binding sites were bidentate in nature. FA were better chelators than the HA fractions. High energy binding sites of both FA & HA were occupied by Fe(III) and the low energy binding sites, mainly responsible for mobilization and immobilization of metal, were occupied by Cu(II).

Feulgen microspectrophotometric estimation of nuclear DNA of species and varieties of three different genera of Marantaceae

Karyological analysis including determination of somatic chromosome number, total chromosome length, volume and karyotype formula andin situ estimation of 4C-nuclear DNA amount were carried out on 14 different species and varieties of the generaCalathea, Maranta andStromanthe. The 4C nuclear DNA amount was estimated through Feulgen microspectrophotometry following single wavelength method and expressed in arbitrary units of relative absorbances. The variation in 4C DNA amounts between the species ofCalathea was not distinct but in two species ofMaranta, a notable variation in nuclear DNA amount was recorded. In addition, the amount of nuclear DNA did not show direct correlation with the total chromosome length and volume. The absence of wide difference in nuclear DNA content at an interspecific level might have some adaptive value.

Improved model calculation of atmospheric CO 2 increment in affecting carbon stock of tropical mangrove forest

Because of the difficulties in setting up arrangements in the intertidal zone for free-air carbon dioxide enrichment experimentation, the responses to increasing atmospheric carbon dioxide in mangrove forests are poorly studied. This study applied box model to overcome this limitation, and the relative changes in present level of reservoirs organic carbon contents in response to the future increase of atmospheric carbon dioxide were examined in the Avicennia-dominated mangrove forest at the land–ocean boundary of the northeast coast of the Bay of Bengal. The above- and below-ground biomass (AGB+BGB) and sediment held different carbon stock (53.20±2.87Mg C ha−1 (mega gram carbon per hectare) versus 18.52±2.77Mg C ha−1). Carbon uptake (0.348mg C m−2s−1) is more than offset by losses from plant emission (0.257mg C m−2s−1), and litter fall (13.52µg C m−2s−1) was more than soil CO2 and CH4 emission (8.36 and 1.39µg C m−2s−1, respectively). Across inventory plots, Sundarban mangrove forest carbon storage in above- and below-ground live trees and soil increased by 18.89 and 5.94Mg C ha−1 between June 2009 and December 2011. Box model well predicted the dynamics of above- and below-ground biomass and soil organic carbon, and increasing atmospheric carbon dioxide concentrations could be the cause of 1.1- and 1.57-fold increases in carbon storage in live biomass and soil, respectively, across Sundarban mangrove forest rather than recovery from past disturbances.

In vitro propagation of Iphigenia indica, an alternative source of colchicine

The present study involves in vitro propagation of Iphigenia indica (Kunth.) through multiplication of whole corms and corm buds. The whole corms produced very small micro-corms, which developed plants individually whereas corm buds multiplied to produce numerous shoots at variable rates in presence of α-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP). The best response in corm and bud multiplication was obtained in Murashige and Skoogs basal medium (MS) supplemented with 2.69 μM NAA and 8.88 μM BAP. The shoots regenerated were further cultured on MS medium containing NAA and indole-3-butyric acid (IBA) for initiation of roots. MS medium with 5.38 μM NAA and 4.92 μM IBA induced highest percentage of roots (81%) within 2 weeks in culture.

Methylglyoxal with glycine or succinate enhances differentiation and shoot morphogenesis in Nicotiana tabacum callus

The aim of this study was to evaluate the influence of methylglyoxal (MG) on organogenesis and regeneration of tobacco (Nicotiana tabacum L.) plants from callus in media containing glycine or succinate. The best improvement in shoot proliferation and shoot length was obtained in the medium supplemented with 0.1 mM MG and 0.5 mM glycine or 0.25 mM succinate. The histological studies showed vigorous development of corm like structures and shoot organogenesis from callus tissues cultured in MG supplemented media. Biochemical studies also revealed higher content of δ-aminolaevulinic acid (a precursor of chlorophyll) and of chlorophyll.

In Vitro Clonal Propagation Through Bud Culture of Hemidesmus indicus (L) R Br: An Important Medicinal Herb

The present study involves in vitro propagation of Hemidesmus indicus (L) R Br through bud multiplication and subsequent plant regeneration. The buds multiplied to produce numerous shoots at variable rates in presence of a-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP) as well as NAA and kinetin. The best response in bud multiplication was obtained in Murashige and Skoog’s (MS) basal medium supplemented with 0.1 mg I-1 NAA and 2.0 mg I-1 BAP (7-8 shoots per explant) and the bud break time was only 4 days after inoculation. The multiplication rate was low when the buds were cultured in NAA and kinetin media and the shootlets regenerated were very thin, weak and elongated. The shoots regenerated were further cultured on MS and half strength MS basal media with variable levels of indole-3-butyric acid (IBA) for initiation of roots. Culture of shootlets for 34 weeks in one half strength of MS medium followed by culturing in the same medium with 1.5 mg 1-1 IBA induced highest production of roots (3-5 roots per shoot) within 2 weeks. Chromosome number stability with no detectable structural changes was observed in the regenerates. The rooted plants were successfully established in the soil with 85% survival rate.

Chromosome Behaviour in Regenerants from Excised Leaf Discs of Solanum Sarrachoides Sendt.

SUMMARYThe present communication deals with the study of chromosome behaviour in plants, regenerated in vitro through direct adventitious bud formation from leaf segments in Solanum sarrachoides Sendt. Highest number of adventitious shoots was obtained in MS semisolid medium supplemented with 2iP (2 mgl−1) as the only growth regulator. Addition of IAA was necessary in the later phase of culture to obtain better growth and development of shoots with well-defined leaves, roots, flowers and fruits. Analysis of the pollen mother and root tip cells of the regenerants showed n = 12 and 2n = 24 chromosomes respectively. Hyperdiploids along with the normal diploid cells were also recorded in low percentage.

Somatic Embryogenesis in Asparagus densiflorus (Kunth) Jessop cv Sprengeri

An efficient protocol has been developed for plant regeneration in Asparagus densiflorus (Kunth) Jessop cv Sprengeri (Asparagaceae) through somatic embryogenesis from spear sections. Callus culture was initiated on Murashige and Skoog (MS) medium formulation containing α-naphthaleneacetic acid (5.37 μM), indole-3-acetic acid (5.71 μM) and 6-benzylaminopurine (2.22 μM). The callus became embryogenic by transferring to 2, 4-dichlorophenoxyacetic acid (4.52 μM) containing MS medium. Somatic embryos developed and matured vigorously on MS medium with NAA (1.07 μM), 6-γ-γ- dimethylaminopurine (9.84 μM) and abscisic acid (1.89 μM). Mature bipolar embryos were converted efficiently into plants on MS medium in the presence of low level of kinetin (2.32 μM). Regenerated plants showed 80% survival after transfer to field. These plants were all diploid (2n=60). Peroxidase activity was maximum in the embryogenic callus as documented from the gel as well as spectrophotometric analysis.